To produce 2,2-dibromo-2-nitroethanol, for example, the following processes are known:
(1) A process wherein potassium hypobromite is reacted with 2-bromo-2-nitro-1,3-propanediol (Chemische Berichte 57B, 2127-2128 (1924)).
(2) A process wherein an alcoholate in alcoholic solution is reacted with 2-bromo-2-nitro-1,3-propanediol, the product is taken out and is suspended in dry ether, and a solution of bromine in chloroform is added to the suspension to carry out bromination (Chemische Berichte 56B, 611 to 620 (1923).
(3) A process wherein 1 mol of nitromethane is condensed with 1.5 mol or more of formaldehyde, followed by bromination with bromine (Japanese Patent Application (OPI) No. 289063/1986).
(4) A process wherein bromine is reacted with nitromethane in the presence of an alkali, followed by reaction with formaldehyde (Japanese Patent Application (OPI) No. 132549/1989).
However, these conventional manufacturing processes are attended by the problems given below and are not necessarily satisfactory for industrially practical processes.
First, the process (1) given above, wherein potassium hypobromite is reacted with 2-bromo-2-nitro-1,3-propanediol, gives a yield of 10.7% (given in the document), which is very low, and therefore the process is not suitable for industrial production at all.
The process (2), which uses 2-bromo-2-nitro-1,3-propanediol as a starting material, is complicated in procedure and gives a yield of 21% (given in the document), which is very low, and therefore the process is not suitable for industrial production.
With respect to the process (3), wherein nitromethane is condensed with formalin followed by bromination, when we carried out the replication of Example 1 shown in Japanese Patent Application (OPI) No. 289063/1986, in the oil fraction, the content of 2,2-dibromo-2-nitroethanol was 57.3 to 62.2%, and the yield was 36.6 to 37.2% based on the nitromethane, and therefore the process could not be satisfactory for industrial production in view of the quality and yield.
With respect to the process (4), wherein formalin is condensed with nitromethane bromide, when we carried out the replication of Example 1 of Japanese Patent Application (OPI) No. 132549/1989, little 2,2-dibromo-2-nitroethanol was formed, despite the description.